Wrong transparency on Backend.draw

[ZZYSonny]

PDF: https://arxiv.org/pdf/2002.10413.pdf
Page: 3 (0 indexed)

pdf-render

pdf-js

The differences are the thick edges (transparency) and the small arrows (position). You can find the call for the left thick edge on the first Backend.draw (matrix(0.87888 0 0 0.87888 127.801 71.99902)), and the arrow (in front of "standard message") has a transformation matrix of matrix(0.87888 0.18372811 -0.18372811 0.87888 127.801 71.99902).